Coating Bath Step Surface Design for Film Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The dip coating method for producing electrophotographic photosensitive members often results in semisolid films forming on the liquid surface during pauses in circulation, leading to retention at the upper-end edge of the coating bath and causing coating defects such as uneven film thickness and non-uniform overflow.
Innovation Solution
A coating apparatus with a cylindrical coating bath featuring a first and second upper-end surface and a step surface, where the circulation can be paused without overflowing, and resumed to flow along the second surface, ensuring the semisolid film is wetted and prevented from retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the circulation of coating liquid is stopped during production intervals, then maintenance operations can be performed on the lowering and lifting unit and liquid transport unit, but semisolid films form on the liquid surface and are retained at the upper-end edge of the coating bath, causing coating defects
Solution Approach 1:
The coating bath is designed with a specific shape (wider at the upper end, narrower at the lower end) before circulation stops, so that when circulation resumes, the liquid flow naturally prevents semisolid films from being retained at the upper-end edge, preemptively avoiding coating defects
Solution Approach 2:
The invention changes the geometric parameters of the coating bath, specifically making the upper end wider than the lower end, which alters the flow dynamics of the coating liquid to prevent semisolid film retention and maintain coating uniformity
2Ease of repair
If the circulation of coating liquid is stopped to exchange filters, then filter maintenance can be performed, but semisolid films form and stay at the upper-end edge portion, resulting in non-uniform coating liquid flow
Solution Approach 1:
The coating bath geometry is预先 designed to be wider at the upper end, so that when circulation resumes after filter exchange, the liquid flow pattern naturally prevents semisolid films from blocking the overflow, ensuring stable and uniform coating liquid flow
Solution Approach 2:
By changing the geometric parameters of the coating bath (upper end width > lower end width), the invention modifies the flow characteristics to maintain coating liquid flow uniformity even after circulation interruptions for filter maintenance
3Productivity
If a single coating apparatus is used for mass production, then productivity is improved, but semisolid film retention causes coating defects that reduce manufacturing precision
Solution Approach 1:
The invention changes the geometric parameters of the coating bath to be wider at the upper end, which prevents semisolid film retention and maintains coating uniformity, enabling high-precision mass production in a single apparatus
Solution Approach 2:
The coating bath shape is designed in advance to preemptively prevent semisolid film formation at the upper-end edge, ensuring that mass production can proceed without coating defects that would compromise precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively suppresses the retention of semisolid films, reducing coating defects and ensuring uniform overflow, thereby improving the mass production of electrophotographic photosensitive members with consistent film thickness.
Implementation Method 1
the overflowed coating liquid flows along the second upper-end surface while wetting the whole area of the step surface
Data Source
AI summary
Provided is a coating apparatus that suppresses the phenomenon in which a semisolid film is retained on the upper-end edge portion of the coating bath even after the circulation of the coating liquid is resumed, resulting in the occurrence of coating defects, and a method for producing an electrophotographic photosensitive member using the coating apparatus. The upper-end portion of the coating bath includes a first upper-end surface, a second upper-end surface that is positioned below the first upper-end surface and has an outer diameter larger than that of the first upper-end surface, and a step surface that interconnects the first upper-end surface and the second upper-end surface. The coating liquid is capable of overflowing from the coating bath, flowing along the second upper-end surface, and flowing while wetting the whole area of the step surface when the circulation is resumed.